CEIsaENTINGf` TOOL WITH INFLATABLE PACKER AND METHOD 0F CEMENTING Filed Sept. 5, 1968 1 4 Sheets-Sheet 4 INVENTOR EUGENE E. BAKER BY mssm MYMTL im 72 ATTORNEYS United States Patent O 3,524,503 CEMENTING TOOL WITH INFLATABLE PACKER AND METHOD OF CEMENTING Eugene E. Baker, Duncan, Okla., assignor to Halliburton Company, Duncan, Okla., a corporation of Delaware Filed Sept. 5, 1968, Ser. No. 757,620 Int. Cl. E21b 33/12 U.S. Cl. 166-289 19 Claims ABSTRACT OF THE DISCLOSURE A well tool which is of the type adapted to be actuated by plug members dropped from the surface. The tool includes a tubular body having a central passage in which are positioned vertically spaced, annular upper and lower members. A first plug member is dropped from the surface to seat on the lower member. A first increase of fluid pressure thereafter moves the lower member down to a fixed final position. A second plug member is then dropped from the surface onto the upper member. A second increase of fluid pressure applied thereafter moves the upper member downwardly. To prevent a body of trapped liquid between the upper and lower members from exerting a hydraulic lock which Would prevent movement of the upper member, the lower member is arranged to separate into at least two parts to permit some of the trapped liquid to escape.

BACKGROUND OF THE INVENTION This invention relates to a well tool of the type adapted to be actuated by plug members dropped down the tool from the surface. In particular, the invention relates to a tool of this type which is particularly suitable for use as a cementing tool.

In cementing a well casing, to provide a layer of cement between the exterior of the well casing and the walls of a well bore in which the casing is situated, it is sometimes advantageous to utilize a process known as multiple stage cementing. In this process, a first stage of cement is forced down the casing to issue from the bottom thereof and pass back up between the casing and the well bore to a predetermined level. To cement the casing above this level, a subsequent stage of cement is forced down through a cementing tool interposed in the casing, with the cementing tool being designed to cause the cement to pass radially outwardly of the tool through radial cementing ports and upwardly therefrom between the casing and the well bore.

ln performing such a two-stage cementing operation, it may sometimes happen that the weight of the second stage of cement exerts such a great pressure upon the underlying first stage as to cause the still unset cement of the first stage to break down the production zone by flowing thereinto. It would therefore be desirable to isolate the weight of the cement in the second stage from the first stage of cement and for this purpose the present invention (as will be discussed) provides an inflatable packer disposed beneath the second stage of cement to isolate its weight from the first stage.

A previous cementing tool for a different, single stage only, cementing operation includes an inflatable packer positioned below a set of cementing ports. A plug passed down from the surface initiates inflation of the packer which is expanded into contact with the well bore after which cement is caused to issue from thev tool. However, this prior tool is specifically intended to avoid issuance of cement below the lower end of the casing and hence could not be used to provide a fully cemented casing with cement extending continuously between the Fice" bottom of the casing string up to the packer and thence up to the surface, as is often desirable.

A two-stage cementing tool for providing a fully cemented casing should therefore provide for issuance of the first stage of cement below the tool with suitable control arrangements being made for subsequent inflation of the packer and issuance of the second stage of cement above the packer. One suitable control arrangement could involve plug members dropped successively from the surface down the tool to control operation of the various members of the cementing tool in the correct sequence.

For example, in a typical arrangement where the packer is inflated by fluid admitted to the interior of the packer from the interior of the tool, the flow of inflating fluid could be controlled by a packer inflation valve moved down to a fixed final position by a first plug member dropped from the surface. After the packer had been set, a cementing valve spaced above the packer inflation valve for controlling the cementing ports might be actuated by a' second plug member dropped from the surface.

With such an arrangement, however, certain problems might be anticipated arising from the unavoidable presence of a body of liquid trapped between the cementing and packer inflation valves. For example, once the packer ination valve had reached its lower position, the body of trapped liquid might function as a hydraulic lock preventing sufficient downward movement of the upper cementing valve to open the cementing ports. If this should happen, it would not be possible to perform the second stage of cementing.

IFurthermore, if some provision were made for permitting escape of some of the trapped fluid to break this hydraulic lock, another problem might then arise in that the consequent drop in the pressure within the cementing tool might cause the inflatable packer to collapse.

SUMMARY OF 'INVENTION It is therefore a general object of the invention to provide a well tool of the type described, which obviates or minimizes problems of the type previously discussed.

It is a particular object of the invention to provide a well cementing tool of the type described having upper and lower valves set by plugs dropped from the surface, wherein the possibility that opening of the cementing ports might be prevented by a hydraulic lock developed between the valves is minimized.

It is another object of the invention to provide a well tool of the type described including an inflatable packer, wherein the inflatable packer may be set in such a manner that subsequent deflation of the packer does not occur even though the fluid pressure within the tool may later fall below inflation pressure.

A well tool according to a preferred embodiment of the invention, intended to accomplish at least some of the foregoing objects is positioned in a well bore. The tool is adapted to be actuated by plug members dropped successively down the tool from the surface. The tool includes a generally tubular body having an axially extending, central passage. A lower member positioned within the tubula-r body includes first and second bodies occupying an initial position within the central passage. The first and second bodies are connected by yieldable, rst connecting means to form a unitary structure. The first connecting means permits at least partial separation between the first and second bodies upon application of a predetermined force to the first connecting means. The second body further includes a lower passage communieating at its lower axial ends with the central passage. A lower seat on the second body is adapted to cooperate with a iirst plug member dropped from the surface to close of't` the lower passage so that a first increase of fluid pressure thereafter applied to the upper side of the first and second bodies causes them to move downward together from the initial position. Limiting means connected to the tubular body limits downward motion of one of the rst and second bodies to a nal position spaced below the initial position thereof. An upper member within the tubular body spaced above the lower member extends transversely of the central passage. The upper member includes an upper passage communicating at its opposite axial ends with the central passage. An upper seat on the upper member is adapted to cooperate with a second plug member dropped from the surface to close off the upper passage so that when a second increase of fluid pressure is thereafter applied to the upper side of the upper member, the upper member moves downward from an initial to a final position. This second increase of pressure is transmitted to a body of liquid trapped between the upper and lower members to apply a force to the irst connecting means at least equal to the predetermined force to cause at least partial separation between the irst and second lower bodies.

In a particular feature of the invention, this separation between the iirst and second lower bodies enables a portion of the liquid trapped between the upper and lower lmembers to escape between the first and second lower bodies, thereby preventing the possibility of hydraulic lock developing between the upper and lower members. Thus, the likelihood that the upper member might be prevented from moving downwardly vdue to the presence of the trapped Huid between the members, is avoided.

In a further significant aspect, the invention is of particular application to a cementing tool. For this purpose, an iniiatable packer sleeve is provided extending about the exterior of the tubular body. Upper and lower seal means at opposite ends of the packer sleeve deiine an enclosed uid tight packer inflation chamber between the packer sleeve and the tubular body. Fluid may be delivered from the central passage to the ination chamber to inflate the packer through a lower, ination port in the tubular body. The iniiation port is closed olf from communication with the central passage by the lower member when the latter occupies t-he initial position. When the lower member is moved down to the final position by the rst dropped plug member, the inflation port is uncovered to admit iluid to the packer to inate it.

In another significant aspect of the invention, a packer pressure lock-in member is provided to insure that the packer continues to remain inliated even though the pressure in the cementing tool may drop later below the ination pressure. For this purpose, the pressure lock-in member is movably mounted in the tubular body for movement across the ination port from a rst position in which the ination port is unobstructed to a second position in which the iniiation port is completely blocked. Pressure responsive means on the pressure lock-in member are acted upon by fluid pressure within the packer chamber to urge the lock-in member from the rst to the second position. Yieldable connecting means between the tubular member and the pressure lock-in member prevent the body being moved to its second position until the Huid pressure in the packer chamber exceeds a predetermined value.

THE DRAWINGS A well tool according to a preferred embodiment of the invention is illustrated in the accompanying drawings in which,

FIG. 1 is a cross-sectional, side view of a well tool according to one preferred embodiment of the invention, with the tool members shown in the relative positions they occupy during running-in of the tool into a well bore;

FIG. 2 is a cross-sectional, side view of a portion of 4 the well tool shown in FIG. 1 in an initial stage of operation of the tool in which an ination valve forming a part of the invention is moved downwardly to admit liquid to the interior of an inatable packer;

FIG. 3 is a cross-sectional, side View of the portion of the well tool shown in FIG. 2 in a next successive stage of actuation in which a packer pressure lock-in member is actuated to lock liquid within the inated packer;

FIG. 3a is a cross-sectional, side view of the well tool in a next successive stage of operation to that shown in FIG. 3, in which a second plug member is dropped from the surface to seat on an upper, cementing valve;

FIG. 4 is a cross-sectional, side view generally corresponding to that shown in FIG. 3a but in a next successive stage of actuation in which the cementing valve is moved downwardly to uncover cementing ports of the tool;

FIG. 5 is a cross-sectional, side view of an upper portion of the well tool shown in FIG. 4 in a iinal stage of operation in which a third plug member is dropped down onto a close off Valve to move the latter down to reclose the cementing ports;

FIG. 6 is a cross-sectional, side view on an enlarged scale of a portion of the well tool shown in FIG. 1, as indicated thereon;

FIG. 7 is a cross-sectional, side view on an enlarged scale of a portion of the well tool shown in FIG. 1, as indicated thereon;

FIG. 8 is a cross-sectional, side view on an enlarged scale of a portion of the well tool shown in FIG. 5 as indicated thereon;

FIG. 9 is a cross-sectional, side view on an enlarged scale of a portion of the well tool shown in FIG. 1, as indicated thereon;

FIG. 10 is a cross-sectional, side view on an enlarged scale of a portion of the well tool shown in FIG. 1, as indicated thereon;

FIG. 11 is a cross-sectional, side view on an enlarged scale of a portion of the well tool shown in FIG. 3, as indicated thereon; and

FIG. 12 is a perspective view of an upper portion of the inlated packer showing the expanded packer slips.

DETAILED DESCRIPTION Principal structure and operation Referring to FIG. 1 of the drawings, a well tool constructed in accordance with a preferred embodiment of the invention is there shown.

The well tool, which comprises a cementing tool, includes a vertically disposed, axially extending, generally tubular body 2 adapted to be interposed in a casing string which is to be positioned in a well bore. The tool body 2 includes an axially extending, internal central passage 4 for the passage of liquid along the tool. An iniatable packer 6 is sleeved about the exterior of the tool body and extends between axially spaced, upper and lower, sealing members 8 and 10. The sealing members 8 and 10 and the packer 6 cooperate with adjacent portions of the exterior of the tool to deline a fluid tight packer chamber 12 (FIG. 2) between the tool and the packer. Liquid may be directed from the central passage 4 into this chamber to inilate the packer, by way of a lower ination port 14.

During the running-in of the tool into the well bore, the port 14 is kept closed to prevent premature iniation of the packer 6. For this purpose, a lower member or iniiating valve 16 closes the port 14 off from fluid communication with the central passage 4. The inflating valve 16 includes concentric, outer and inner (or iirst and second) annular bodies 18 and 20, respectively. These bodies are held together in closely fitting, concentric relation to form a unitary structure extending completely across the central passage 4, by a tirst shear pin 22. The lower member 16 is held in an initial position overlying and closing off the entrance to the inflating port 14, by a second shear pin 24. Liquid may pass through the lower member 16 via a lower passage 26 extending axially entirely through the second body 20.

In the use of the tool for multiple stage cementing, the tool is interposed in a casing string which is run in to the well bore. The first stage of cement is pumped downwardly through the tool and casing to emerge from the bottom of the casing string and pass back up between the casing and the well bore. A displacement -iiuid such as drilling mud or water is used to force the first stage of cement out of the casing. Double stage cementing operations of this type are described for example in the United States Pitts Pat. No. 2,435,016 and on page 47 of the 1968 Sales and Service Catalog of Halliburton Services, Duncan, Okla.

When it is desired to commence the second stage of cementing, a first plug member 28 (FIG. 2) is passed down the casing by gravity through the displacement ud to seat on the second body to close o the lower passage 26. The plug member 28 is shown as of the spherical ball type, however, the plug members may be of configured as a bomb or be of other conventional shapes as desired. Then a first increase in the fluid pressure is applied to the liquid above the lower member 16. When the rst increase in pressure exceeds a predeter mined value, the pin 24 shears and the lower member 16 (comprising the still connected first and second bodies) moves axially down the tube from the initial position to uncover the entrance to the inuation port 14. The lower member 16 and plug 28 move down to a second position in which further downward motion of the outer body 18 is prevented. This occurs due to contact of the outer body with a shoulder 29 (FIG. 2) provided by the upper end of a length 29a of casing string connected below the tool. Alternatively, downward motion of the outer body 18 may be limited by frictional binding between its exterior peripheral surface and the rough interior surface of the lower casing string 29a. At this time the lower member 16 (still connected to the outer body 18) and the plug 28 completely obstruct the central passage 4 so that pressure builds up in the liquid above the lower member. Displacement liquid under pressure thus passes into the packer chamber 12 to expand the packer firmly against the walls of the well bore. Alternatively, it would be possible to utilize cement as a packer inflation uid under special circumstances where this might be desirable.

Once the packer 6 has been set, it is advisable that it should remain set, even despite any subsequent drop in pressure in the central passage 4 to a pressure below that necessary to maintain packer iniiation. For this purpose a packer pressure lock-in member 30 is movably mounted in the tool body 2 for motion relative to the lower inflation port 14. Initially (FIG. 2) the pressure lock-in member 30 does not cooperate with the inflation port 14 to obstruct the ow of liquid through this inflation port into the packer chamber. However, when the pressure within the packer chamber exceeds a predetermined value (FIG. 3) the pressure lock-in member 30 moves downwardly to completely obstruct the mouth of the port 14 so that liquid may not thereafter pass either into or out of the packer chamber 12. This insures that the packer 6 remains inflated regardless of whatever pressure changes occur in the central passage 4 thereafter. It is also significant that the pressure lock-in member 30 also insures that excessively high pressures likely to damage the packer cannot thereafter be applied to the interior of the packer chamber 12.

Once the packer 6 has `been set, it is then necessary to open a set of radially extending, cementing ports 31 in the upper part of the tool body 2 spaced above the packer 6 for subsequent displacement of a second stage of cement radially outwardly of the tool body. During running in of the tool, these ports 31 are closed olf from the central passage 4 by an upper member or cementing valve 32. In an initial position, valve 32 overlies the cementing ports 31.

The upper member 32 comprises an annular body fitting snugly against the interior of the tubular body 2. This body has an upper passage 34 extending entirely axially through the upper member 32 to permit the passage of liquid through the central passage. The upper member 34 1s held against motion from its initial position by upper shear pins 36.

Tocommence the second stage of cementing, a second ball-like plug 38 (FIG. 3a) generally similar to the first but of relatively large diameter is passed by gravity down the casing through the displacement liquid to seat on the upper member 32 and thus close off the central passage 4. A second increase of fluid pressure is then applied to the liquid above the cementing Valve comprising member 32 and ball 38. When the second increase in liuid pressure exceeds. a predetermined value, the pins 36 shear and the cementing valve moves down to uncover the cementing ports 31 (FIG 4). Cement forced down the casing thereafter passes out through the ports 31 and is forced into the space between the casing and the well bore extending upwardly above the packer 6 to provide the second stage.

particular feature of the invention resides in the provision of structure for obviating problems of hydraulic loclr existing due to the presence of a column of trapped liquid 39 between the lower, packer iniiation valve 16 (seated on the shoulder 29) and the upper, cementing valve 3.2. If there were no path of escape for this trapped liquid, 1t would not be possible to force the upper valve 32 and plug 38 downwardly to a sufficient extent to clear the ports 31 so that the second stage of cementing could c ommence. To avoid this problem, the previously mentioned shear pin 22 connecting the first and second bodies 18 and 20 is arranged to shear when the second increase of pressure applied to the upper valve member, which is transmitted through the trapped volume of liquid 39 to the lower member 16, exceeds a predetermined value. This permits the inner body 20 and the plug 28 to separate downwardly (FIG. 4) from the outer body 18 so that some of the trapped liquid may escape. This arrangement thus enables suiiicient downward movement of the upper valve body to expose the connecting ports 31 so that the second stage of cementing may be effected.

Once the inner and outer bodies 20 and r18 of the lower member 16 have separated, the pressure within the cementing tool below the upper member of course drops. However, this does not cause the packer 6 to deflate by reason of the action of the previously discussed pressure lock-in member 30.

When the second stage of cementing has been completed, it is then necessary to close the cementing ports 3.1: For this purpose a close off valve 42 (FIG. 4) is positioned within the central passage above the cementing valve 32. The close olf valve 42 comprises an annular, sleeve-like body sealingly abutting the interior of the tool body 2. This sleeve-like body is provided with a passage 44 extending entirely axially through the close off valve to permit cement to ilow through the central passage of the tool. To actuate the close off valve 42, a third plug 46 (FIG. 5) is passed down the casing to seat upon the close off valve 42 to completely obstruct the passage 44. A third increase in fluid pressure is applied to the upper side of the close ofi valve 42 and the third plug 46 to force the close 01T valve 42 downwardly until it overlies the cementing ports 31 to colse them off.

DETAILED STRUCTURE The previously mentioned tool body 2 (FIG. 1) which is of cylindrical or tubular form has a uniform diametered, internal, main bore wall 60 and a concentric, external peripheral surface 62. The tool body 2 is threaded at its upper and lower extremities for connection with a conventional casing string as described generally in the aforesaid Pitts patent.

To receive the packer 6, the tubular body 2 is provided with an annularly recessed, axially extending channel 63 (FIG. 2) about its exterior surface. The channel 63 is defined by an exterior, axially extending, peripheral surface 64 spaced radially inwardly of the exterior surface 62, and by upper and lower, radial shoulders 66 and 68. The packer 6 includes axially extending, inner and outer, concentric sleeves 70 and 72, respectively, of elastomeric material. An intermediate sleeve 74 of braided wire sheathing is interposed between the inner and outer elastomeric sleeves.

At its upper end, the packer 6 is secured to the previously mentioned upper seal member 8 (FIG. 9). The seal member 8 includes an annular metal body 76- fitting slidably and snugly about the recessed portion 64 of the exterior surface of the tool body and abutting the shoulder 66. Projecting downwardly from the lower end of the body 76 is a projecting annular lip 78 having an inner surface 78a inclined downwardly and away from the adjacent surface 64 of the tool body. The inner elastomeric sleeve 70 at its upper end is bonded to the inner surface of the lip 78. Bonded to the outer surface of the outer sleeve 72 adjacent the upper end thereof is a floating metal annular ring 80, abutting contacting the body 76 at its upper end. Overlapping and extending about the body 76, and the floating ring member 80 as an exterior, annular member 82 ixedly secured to the body 76 by a threaded elongate connector 84. The metal ring 80 and the annular lip 78 are provided with opposed spaced serrated surfaces 80h and 78b facing toward each other. The surfaces 78b and 80h are inclined downwardly and radially outwardly away from the tool body and grippingly and wedgingly engage the upper end of the braided metal sheath 74. Outward bulging of the packer tends to pull the oating ring member 80 downwardly relative to the outer member 82 and the body 76, however, this causes the inclined face 80b to bite more deeply into the sheath '74 thus anchoring the packer more firmly to the seal member 8. Additionally, the outward inclination of the serrated faces 80b and 78b in the direction in which the packer bulges outwardly is of particular value in avoiding high stress concentrations in the metal sheath about either of the outer extremities of the faces 8017 and 70h. Such strain concentrations, which might be caused by bending of the sheath about either of these extremities when the sheath assumes its inated shape, are avoided by inclining the serrated faces generally into alignment with the adjacent portions of the inated packer.

A plurality of axially extending, peripherally spaced, metal slip fingers 86 extend downwardly from and are connected with the external annular member 82. The iingers are sufciently exible (FIG. l2) to ex radially outwardly in contact with the packer when it is expanded. The slip fingers 86 carry externally serrated wicker faces 86a to grip the well bore when the packer is expanded to assist in supporting the packer against axial movement in the well bore due to diiferential pressure across it and to reinforce and stabilize the packer. This construction wherein the slip ngers remain integrally connected with the annular member 82 even when expanded is partlcularly advantageous in maintaining the tool centered in relation to the expanded packer.

To provide a uid tight seal between the packer 6 and the tool body, two axially spaced, peripherally extending, resilient seal rings 88 are mounted in the body 76 of the seal member 8 facing toward and sealingly contacting the surface 64.

To xedly locate the upper seal member 8 vertically relative to the tool body when the tool is being run in, a shear pin 90 (FIG. 1) extends between the tubular body 2 and the upper seal member 8. However, when the packer 6 is expanded, the pin 90 shears to permit the upper seal member 8 to move downwardly (FIG. 2) as the packer 6 bulges outwardly shortening its length.

The lower, annular seal member is connected with Cil the packer 6 in a generally similar manner to that described for the upper seal member 8. However, the lower seal member .10 is not axially movable along the tool body 2 but is xedly connected to an annular wall 92 (FIG. 3a) integral with the tool body 2 and extending upwardly about the periphery of the previously mentioned lower shoulder 68, by an annular detent 93 extending between the lower seal member 10 and the wall. Suitable seal rings (not shown) are interposed between the wall 92 and the lower seal member 10.

Extending upwardly from the lower seal member about the lower part of the packer r6 are a set of lower serrated slip fingers 93, similar to the previously described upper slip ngers 86 and for a like purpose.

Displacement liquid, such as the aforementioned drilling mud, is admitted to the interior of the packer 6 to inflate it through the previously mentioned ination port 14. The intiation port 14 includes an entry opening 98 (FIG. 10) extending transversely from the central passage 4 and communicating with an axially extending passage within the wall thickness of the tool body 2. The axial channel 100 includes a lower bore portion 100g of relatively enlarged diameter intersected by the previously mentioned entry bore 98, and an upper bore portion 100b of relatively smaller diameter than the lower bore portion. The lower bore 10M at its lower end communicates with fluid in the casing through a radial communication port 101 in the tool body. Ihe upper bore 100b intersects the previously mentioned lower shoulder 68 (FIG. 2). Liquid is conducted from the upper end of the bore 100b between the surface 64 and a spaced adjacent interior surface of the lower seal member 10, into one or more recesses 102 in the surface 64 extending longitudinally to almost the mid-:point of the packer 6. These recesses communicate with the chamber 12, with the ridge-like wall portions yof surface 64 between these grooves serving to hold the packer 6 out of the grooves 102.

Interposed in the large bore portion 100a (FIG. 10) is the previously'mentioned packer pressure, lock-in member 30. The lock-in member includes a cylindrical body 104 snugly and slidably received in the bore 100a. An upper end of the body 104 abuts a shoulder 106 at the intersection of the bores 100a and 10011. The body 104 is held in this initial position by a shear pin 108 extending between the body 104 and the tool body 2.

An axial bore 110 in the lock-in member body 104 has an open upper extremity communicating with the bore 100b, and a closed lower extremity. A transverse bore 112 in the body 104 places the bore 110 in uid communication with the entry opening 98 so that liquid may flow from the interior passage 4 of the tool into the packer chamber 12.

When the pressure differential between the pressure in the packer chamber 12 and the pressure prevailing at the lower end of the bore 100a externally of the pressure lock-in member 30 (transmitted from the fluid externally of the casing through the port 101) reaches a predetermined value, the pin .108 shears and the pressure lock-in member moves downwardly (FIG. 1l). At this time the transverse port 112 moves out of registry with the entry port 98 so that liquid ow into the packer teruninates, thus locking the existing pressure with the packer. Thereafter any subsequent change in pressure in the central passage 4 (whether increase or decrease) is isolated from the packer so that it remains expanded. In addition, the packer is not subjected to any excessively high perssures which might develop in the central passage 4 and might otherwise cause packer damage.

To prevent high pressure uid from creeping between the exterior of the pressure lock-in member 30 and the walls of the bore 100a, upper and lower pairs of axially spaced, peripherally extending seal rings 114 are mounted sealingly between the body 104 and the walls of the bore 10011.

To prevent the pressure lock-in member 30 from falling out below the bottom of the bore 100a, a plug 116 is mounted in the bottom of the bore 100a, upon which the pressure lock-in member 30 rests once it is moved to its lower position. Movement of the pressure lock-in member 30 back to its initial position is prevented by an expanding spring clip or lock-in ring 118 mounted about the periphery of the lower part of the body .104. The clip passes into an enlarged chamber 120 in the bore 100a and expands. Upward movement of the body thereafter is prevented by impingement of the clip 118 on a shoulder 122,defining the upper part of the chamber 120.

Liquid is initially prevented from entering the entry opening 98 of the inflation port 14, as previously discussed, by the lower member or ination valve 16 (FIG. In detail, the outer body 18 of valve 16 which is formed as a cylindrical collar, overlies and extends axially above and below the port 98. Upper and lower, axially spaced, peripherally extending seal rings 120 are provided between the collar 18 and the adjacent interior surface 60 of the tool body to prevent leakage of fluid into the entry port 98. The inner body of valve .16 is positioned snugly and concentrically within the outer body 18 and is secured thereto by the previously mentioned shear pin 22. The outer diameter of the inner body 20 is less than the internal diameter of the lower casing string 29a so that once sheared, liquid may bypass the separated inner body between the inner body and the casing. The inner body 20 also includes a downwardly and radially inwardly tapered lower seat 122. Additional axially spaced, peripherally extending seal rings 124 are interposed between the adjacent surfaces of the inner and outer bodies 20 and 18 to prevent leakage of iiuid between the bodies when they are in the connected condition.

When the irst plug 28 is passed down the casing, the plug seats on the seat portion 122 to close the lower passage 26 and prevent further liquid flow through the lower member 16. Thereafter the displacement liquid above the lower member is subjected to a steadily increasing rst increase in pressure until eventually the previously mentioned shear pin 24 shears. This shearing permits the first and second bodies 18 and 20 (still xedly connected together by the shear pin 22) to move downwardly. As the lower member moves down, the entry port 98 becomes uncovered.

Eventually, the outer body 18 moves into abutting contact with the previously mentioned shoulder 29. The shoulder 29 comprises the upper end of a thick walled casing section mounted between the lower end of the tool 2 and the next lower length of casing. This casing section 29a is of sutiicient internal diameter so that the shoulder 29 contacts only the outer body 18 and not the inner body 20.

With the plug 28 and lower member 16 blocking the central passage 4 and seated in shoulder 29, it is possible to build up sufficient pressure in the central passage to force displacement liquid into the chamber 12, with sufficient force to expand the packer 6. Eventually, as pressure builds up still further, the pressure lock-in member 30 is operated, as just discussed, to isolate the packer chamber from the central passage 4.

In the unlikely event that the rst plug 28 might accidentally cause the inner body 20 to separate from the outer body 18 prior to separation of the outer body 18 from the tool body (for example, if a defective shear pin 22 should accidentally be installed) it would be desirable to provide some alternative route whereby the packer 6 could still be inflated. For this purpose the outer body 18 is provided with a peripherally extending, outer groove 124 (FIG. l0) communicating with the entry opening 98 to the inflation port 14. A plurality of peripherally spaced, transverse ports 126 extend through the outer body 18 from the groove 124 to the interior. If the inner body 20 should accidentally separate lirst from the outer body 18, liquid may still pass to the packer 6 to 10 inllate it through the ports 126, the groove 124 and the inflation port 14.

The passage of the second stage of cement out of the tool is (as initially mentioned) controlled by the upper valve 32 (FIG. 6). The upper valve 32 is mounted within an upper, recessed portion of the inner wall surface 60 of the tool body. Valve 32 comprises a generally cylindrical body slidingly contactingthe interior surface 130. In the initial position, an upper part 32a of the upper valve 32 overlies the cementing ports 31, with the upper valve 32 being held in position by the previously mentioned upper shear pins 36. Suitable, peripherally extending, seal rings 132 are interposed between the upper valve 32 and the adjacent interior surface 130, above and below the cementing ports 31, to prevent seepage of liquid between the upper member and the cementing ports.

Secured to the interior of the upper valve member 32, adjacent the lower part thereof, and extending radially inwardly, is an annular seat member 134. The seat member 134 includes a central opening or upper passage 13S which, at its throat, is of larger diameter than the diameter of the previously mentioned rst plug member 28. This permits the first plug member 28 to pass through the cementing valve without interference. Above the throat of the passage 135 is a frustoconical seat surface 136 on which the previously mentioned second plug 38 (which is of larger diameter than the rst plug 28) seats to close 01T the passage 135. The second increase of pressure is built up above the now closed upper valve 32 until the pin 36 shears and the cementing valve commences to move downwardly. However, the previously mentioned body of trapped liquid 39 between the upper and lower valves is of course incompressible and would normally prevent downward movement of the cementing valve to a sufficient extent clear the cementing ports 31. The initial small downward movement to shear the pin 36 is usually taken up by compression of usual voids within the liquid, however, there are not generally suicient voids to permit the trapped body 39` to be compressed a suilicient amount for the valve to move down far enough to clear the cementing ports 31.

However, the second increase of pressure is transmitted through the trapped body of liquid 39` and is thus applied to the ball 28 and inner member 20, thereby tending to 'move them downwardly relative to the outer member 18.

Outervmember 18, of course, is fixed in position by virtue of its abutting contact against the shoulder 29. Eventually, the pressure differential builds to a suiiicient value to shear the pin 22. Once the pin 22 has sheared, the inner body 20 and the plug 28 are free to pass on down the casing (FIG. 4) so that some of the trapped iluid 39 between the upper and lower valves may escape. This releases the hydraulic lock so that the upper member 32 may move downwardly to a suicient extent to uncover the cementing ports 31.

Cement is then forced down to pass outwardly of the cementing ports 31 until the second stage of cementing is completed.

It will be appreciated that the weight of the second step of cement is supported on the inflated packer and is thereby isolated from the first stage of cement extending below the packer. This is particularly important as it avoids applying a high pressure to the rst stage of cement which might otherwise cause it to break down a production zone in the well bore surrounding the rst stage.

Eventually, the upper valve member 32 moves downwardly to a second position. In this position, Valve member 32 abuts a shoulder 138 (FIG. 8) positioned at the intersection between the recessed and main bore portions 130 and 60, respectively, of the tool body 2.

After the second stage of cementing has been completed, the close olf valve `42 is actuated to reclose the cementing ports 31.

resilient, deformable, peripherally extending seal rings 146 are interposed sealingly between the adjacent surface of the close off valve 42 and the tool body.

Adjacent its lower end, the close off valve 42 is provided with an integral, downwardly depending, annular lip 148 spaced from and parallel to the surface 130 of the tool body. The close off valve 42 is held in an initial position, in which the lip 148 is spaced above the cementing ports 31, by a shear pin 150. At its upper end, the body 144 is provided with an inwardly projecting constricted member 152 provided with an axially extending passage 154. The passage 154 at its narrowest throat portion is of suiciently large diameter to permit the previously mentioned second plug 38 for actuating the cementing valve to pass through without interference.

When it is desired to operate the close off valve 42, the third plug `46 (which is of larger diameter than the second plug 38) is passed down the casing to seat on an upper seat 158 provided on the upper constriction member 152. The third plug 46 differs fromr the first and second plugs 28 and 38 in that it is not a bomb plug adapted to fall under its weight through the liquid in the casing. Instead, the plug 46 is a wiper plug (generally similar for example to the type of plug disclosed in FIG. of the aforesaid Pitts patent) which is pumped down the casing by fluid pressure. Thereafter the initially described, third increase of pressure above the close off valve 42 is effected until a predetermined value is exceded. At this time, the shear pin 150 shears to permit the close off valve 42 to move downwardly. As the close off valve 42 moves downwardly, the valve moves into overlapping relation over the cementing ports 31 to close them off. At the same time the previously mentioned lip 148 moves slidably and sealingly into a mating, internal annular recess portion 160 provided on the upper member 32. Suitable seal rings 162 are mounted peripherally about the lip 148 providing a seal between the lip 148 and the adjacent portions of the upper member 32.

To avoid development of a hydraulic lock between the second and third plugs similar to that discussed between the first and second plugs, the close off valve 42 is provided with peripherally spaced relief ports 170 (FIG. 7) extending transversely between the throat of the constricted portion 152 and the exterior thereof. A plurality of resilient deformable ball valves 172 are held in closing contact against the exterior ends of the relief ports 170 by cage structure, generally designated 174, connected with the close ofi valve 42. As pressure above the close off valve 42 and the third plug 46 is increased, trapped cement between the close olf valve and the cementing valve exerts pressure through the relief ports 170 upon the resilient deformable ball valves 172. Eventually, the pressure is sufficient to deform the ball valves sufficiently to unseat so that cement may escape above the close off valve through axial passages 176. In this way problems of hydraulic lock are obviated.

SUMMARY OF ADVANTAGES It will be appreciated that in constructing a well tool according to the present invention, certain significant advantages are provided.

Of great importance is the provision of an inflatable packer in a two-stage cementing method to isolate the weight of the second stage from the first stage. This avoids the possibility of exerting such a high pressure on the first stage that it might cause breakdown of the production zone.

In particular, the tool provides a cementing tool of the inflatable packer type in which the operations of infiating the packer and of opening the cementing ports may be performed simply, reliably and at low cost by the use of plug members passed down from the surface.

Of special advantage is the manner in which the shearable lower member separates into two parts to prevent the possibility of a hydraulic lock developing between the lower, packer inflation valve and the upper cementing valve. In more detail, the possibility that a body of trapped cement between the upper and lower valves might prevent the cementing valve from moving sufiiciently down to uncover the cementing ports is obviated by the provision of the separable inner body in the lower member which permits escape of the trapped fluid.

Also very significant is the provision of the packer pressure lock-in member which insures that the packer does not subsequently deflate whenever the pressure within the cementing tool drops below inflation pressure. Such drop, for example, occurs when the lower member separates into the two parts to permit escape of the trapped fiuid.

Other important advantages are provided by the slip lingers which maintain the shape and stability of the iniiatable packer in relation to the tool `and protect the packer against ballooning effects once expanded.

In addition, the lock-in member is of particular value in preventing excessively high pressures within the cementing tool from being applied to the packer.

I claim:

1. A well tool for use in well bore, adapted to be actuated by plug members dropped down the tool from the surface, the tool comprising:

a longitudinally extending, generally tubular, body having, an axially extending central passage; longitudinally spaced upper and lower members within said central passage, said lower member including,

first and second bodies occupying an initial longitudinal position relative to said tubular body, yieldable first connecting means fixedly connecting said first and second bodies together to form a unitary structure, said first connecting means upon application of a predetermined force thereto permitting at least partial separation between said first and second bodies, said second body further including,

a lower passage communicating at opposite axial ends thereof with said central passage, a lower seat adapted to cooperate with a rst plug member dropped from the surface to close off said lower passage so that a first increase of fluid pressure thereafter applied to the upper side of said first and second bodies causes said first and second bodies to move longitudinally together from the initial position;

limiting means connected with said tubular body for limiting longitudinal motion of one of said first and second bodies to a final position spaced longitudinally below the initial position thereof when said tool is disposed in a well bore;

said upper member including,

an upper passage communicating at opposite axial ends thereof with said central passage,

an upper seat adapted to cooperate with a second plug member dropped from the surface to close off said upper passage so that a second increase of fluid pressure thereafter applied to the upper side of said upper member causes downward movement of said upper member from an inital position thereof, said second increase of fluid pressure being transmitted through a body of liquid trapped within said central passage between said upper and lower members to apply a force to said first connecting means at least equal to said predetermined force to cause at least partial separation between said rst and second bodies, such separation permitting escape of a portion of said trapped liquid to prevent a hydraulic lock between said upper and lower members.,

2. A well tool as defined in claim 1 further including:

an axially extending, annular, inflatable packer, said packer being sleeved about the exterior of said tubular body;

upper and lower seal means adjacent opposite axial ends of said packer extending between said packer and said tubular body to define an annular, fluid tight, inflation chamber between said packer and said tubular body; and

lower port means in said tubular body for delivering fluid from said central passage to said inflation chamber to cause inflation of said packer, said lower port means being closed off from fluid communication with said central passage by one of said first and second bodies when said bodies occupy the initial position thereof, with movement of said bodies from said initial position to said final position, uncovering said lower port means to permit entry of fluid into said inflation chamber.

3. A well tool as defined in claim 2 further including:

upper port means in said tubular member spaced above said packer, said upper port means for directing fluid from said central passage transversely outwardly of said tubular body, said upper port means being initially closed off from fluid communcation with said central passage by said upper member in the initial position thereof.

4. A well tool as defined in claim 2 further including,

yieldable second connecting means extending between said tubular body and said lower member to prevent movement thereof from the initial position until said first increase of fluid pressure exceeds a predetermined amount.

5. A well tool as defined in claim 2 further including:

a pressure lock-in member movably mounted in said tubular body, said pressure lock-in member including,

a lock-in body movable relative to said lower port means from a first position, in which said lock-in body does not block said lower port means, to a second position in which said lock-in body blocks said lower port means to prevent a flow of liquid between said central passage and said inflation chamber,

pressure responsive surface means acted upon by the fluid pressure in said inflation chamber, said pressure responsive surface means being connected with said lock-in body and operable to urge said lock-in body from said first position to said second positionLand yieldable, second connecting lmeans between said lock-in body and said tubular member for preventing motion of said lock-in body from said first position thereof until the fluid pressure in said inflation chamber exceeds a predetermined value.

6. A well tool as defined in claim 1 wherein:

said first body defines a generally annular outer body fitting slidably and snugly against the adjacent inl terior surfaces of said tubular body,

and wherein said second body defines a generally annular inner body positioned concentrically and snugly within said outer body.

annular, resiliently deformable seal means carried by said gripping means extending sealingly be tween said gripping means and adjacent exterior portions of said tubular body, and

means connecting said gripping means with said tubular body to permit relative axial movement of said gripping means along said tubular body upon inflation of said packer.

9. A well tool as defined in claim 3 further including:

stop -means connected with said tubular body for limiting downward axial motion of said upper member to a final position spaced below the initial position of said upper member;

a close-off member positioned within said tubular body, said close-off member, in an initial position thereof, being spaced above said upper member in the upper position thereof, said close-off member including,

a passage having opposite axial ends thereof communicating with said central passage,

a seat adapted to cooperate with a third plug member dropped from a well head to close off said passage of said close-off member, so that a third increase of fluid pressure thereafter applied to the upper end of said close-oliP member causes downward movement to a final position thereof;

said upper and close-off members including,

interengaging portions, said portions being operable to mutually engage and close off said upper port means from said central passage when said upper and cooperating members are in the respective final positions thereof.

10. A well tool as defined in claim 9 further including:

yieldable second connecting means extending between said tubular body and said upper member to prevent downward movement thereof from the initial position until said second increase of fluid pressure exceeds a predetermined value; and

yieldable third connecting means extending between said tubular body and said close-off member to prevent downward movement thereof from the initial position until said third increase of fluid pressure exceeds a predetermined value.

11. A method of multistage cementing of a casing in a well bore comprising the steps of interposing an inflatable packer in the casing intermediate the ends thereof, the inflatable packer commicating with inflation port means initially closed by lower valve means and being below an upper port means initially closed by upper valve means,

disposing the casing and packer in the well bore,

forcing at least one initial stage of cement down through the casing to issue below the packer and pass back up between the casing and the well bore to a level generally below the level of the packer,

actuating the lower valve means to open the inflation port means and to close off the inflatable packer from the central casing passage below the lower valve means,

forcing liquid under pressure into the interior of the inflatable packer to inflate it firmly against the well bore,

actuating the upper valve means to open the upper port means and to close off the central casing passage below the upper valve means,

relieving fluid trapped between the upper valve means and the lower valve means to avoid a fluid lock, and

lwhile the packer remains inflated forcing a second stage of cement outwardly of the casing above the packer to pass upwardly therefrom between the packer and the well bore.

blocking exit of the liquid forced into the inflatable packer from the packer to cause the packer to remain permanently set once inflated. 13. A cementing tool for multistage cementing of a casing string within a well bore, the tool comprising:

a tubular body adapted to be inteposed in the casing string with said tubular body extending vertically when disposed in the well bore, said tubular body having a central passage;

an inflatable packer sleeved about a central portion of said tubular body,

seal means extending between said packer and said body for providing a fluid tight packer infiation chamber between said packer and said body,

vertically spaced upper and lower port means in said tubular body for conducting liquid outwardly of said central passage above and below said packer,

inflation port means in said tubular body for conducting liquid from said central passage to said packer inflation chamber for inflation of said packer,

said upper and lower valve means being selectively and separately operable to open said upper port means said inflation port means respectively and being adapted to trap between said upper and lower valve means, and

a first annular valve, including first and second bodies, slidably mounted within said tubular body closing off said inflation port means from said central pas sage, said annular body adapted to seat a first plug passed down the casing string so that a subsequent first increase of fluid pressure thereabove moves said first annular body down to uncover said infiation port means;

and wherein said upper valve means includes,

a second annular valve slidably mounted within said tubular body closing off said upper port means from said central passage, said second annular body adapted to seat a second plug passed down the casing string so that a subsequent second increase of fluid pressure thereabove moves said second annular body down to uncover said upper port means;

said fluid lock prevent means including,

connecting means fixedly connecting said first and second bodies together to form a unitary structure, said connecting means upon application of a predetermined force thereto permitting a least a partial separation between said rst and second bodies.

15. A cementing tool for multistage cementing of a casing within a well bore, the tool comprising:

a tubular body adapted to be interposed in the casing string with said tubular body extending vertically when disposed in a well bore, said tubular body having a central passage;

an inflatable packer sleeved about a central portion of said tubular body,

seal means extending between said packer and said body for providing a fluid tight packer inflation chamber between said packer and said body,

vertically spaced upper and lower port means in said tubular body for conducting liquid outwardly of said central passage above and below said packer,

inflation port means in said tubular body for conducting liquid from said central passage to said packer inflation chamber for inflation of said packer, and

vertically spaced upper and lower valve means closing off said upper port means and said inflation port means respectively from said central passage, said upper and lower valve means being selectively and separately operable to open said upper port means and said inflation port means respectively.

said packer further including axially extending, spaced, concentric inner and outer sleeves of elastomeric material,

an intermediate sleeve of braided metal sheathing interposed between said inner and outer sleeves;

said seal means including upper and lower seal means connected with the upper and lower ends of said packer respectively, at least one of said upper and lower seal means further including,

a rigid annular main body extending sealingly around said tool body,

a fixed ring fixedly connected with said main body extending about said tubular body, said fixed ring fixedly connected to one of said inner and outer sleeves,

a floating ring extending about said tubular body, said fioatin g ring fixedly connected with the other of said inner and outer sleeves,

guide means connected with said main body contacting said oating ring to guide said floating ring for axial, concentric motion relative to said fixed ring,

said fixed and floating surfaces including,

spaced, opposed, lperipherally extending wedging surfaces grippingly engaging opposite sides of said intermediate sleeve, said wedging surfaces being radially outwardly inclined in a direction to incline said surfaces generally in the direction of adjacent portions of said intermediate sheath when said packer is inflated. 16. A cementing tool as defined in claim 15 further including including relief valve means in said close off members for permitting upward escape of fluid through said close off valve upon exceeding a predetermined upward pressure differential to prevent a hydraulic lockbetween said second and third plug members. 18. A Well tool including: a longitudinally extending body adapted to be disposed vertically when in a well bore, a longitudinally extending, generally tubular, infiatable packer sleeved about the exterior of said body, first and second seal means connected with said body and with said packer at opposite longitudinal ends thereof for defining a fluid tight infiation chamber between said packer and the adjacent exterior portions of said body, port means in said body for selectively admitting liquid under pressure into said inflation chamber for infiating said packer, each of said seal means including,

a rigid metal collar sleeved about said body, a plurality of slip fingers integral with and spaced about said collar extending longitudinally away 17 therefrom in overlying Contact with adjacent portions of said packer, and outwardly facing serrated surfaces on said slip ngers, said slip lingers being flexed radially outwardly by said packer upon expansion thereof to force said serrated surfaces into gripping contact with the well bore. 19. A well ltool as defined in claim 18 including, irst means connecting one of said collars in fixed axial relation with said body, shearable second connecting means for locating the other of said collars axially in relation to said body, said second connecting means shearing upon inflation of said packer to permit said other collar to move axially of said body.